Bertha w



April 24, 1928. 1,666,981

c. s. SOMERVELL IMPACT on PERCUSSIVE TOOL OF THE EXPLOSIVE MOTOR TYPE Filed Aug. 25

5 Sheets-Sheet 1 INVEN TOR 67/07/25 fifzxarhj'omerye/l HTTORNEYJ WITNESS April 24," 1928. 1,666,981

c. s. SOMERVELL IMPACT OR PERCUSSIVE TOOL OF THE EXPLOSIVE ROTOR TYPE Filed Aug. 25, 1923 April 24. 1928. 4 1,666,981

c. s. SOMERVELL 1 IMPACT OR PERCUSSIVE TOOL OF THE EXPLOSIVE MOTOR TYPE Filed Aug. 25, 1923 5 Sheets-Sheet 4 April 24. 1928. 1,666,981

c. s. SOMERVELL IMPACT OR PERCUSSIVE TOOL OF THE EXPLOSIVE MOTOR TYPE Filed A 25, 1925 5 Sheets$heet 5 Patented Apr. 24, 1928.

UNITED STATES PATENT OFFICE.

CHARLES STUART SOMERVELL, OF RIVERTON, NEW JERSEY; BER-TEA \V. SOMERVELL ADMINISTRATRIX OF SAID CHARLES STUART SOMERVELLL, DECEASED, ASSIGNOR TO PENNSYLVANIA GASOLINE DRILL COMPANY, OF PHILADELPHIA, PENNSYL- VAN IA, A CORPORATION OF DELAWARE.

IMPACT OR PERCUSSIVE TOOL OF THE EXPLOSIVEJVIOTOR TYPE.

Application filed August 25, 1923.

My invention relates to a type of drill, hammer or similar impact device in which a unitary piston-hammer is reciprocated with in a cylinder to impart a heavy impact to a tool. such as a drill or a drill-bit, or a riveting, or a digging tool or similar tools, the movement of such piston-hammer being derived from the combustion of an explosive mixture under compression in one end of the cylinder.

The structure forming the subject-matter ot the present invention includes a cylinder and an impact piston or piston-hanmier reciprocating within the cylinder on the principle ot a single-acting two-cycle combustion engine in that fuel is drawn into a mixing or transfer chamber on the compression stroke, is initially compressed in the said chamber on the working stroke, is transferred under pressure to the combustion end of the cyliiuler to expel the products of combustion of the previous working stroke at the end ot; the working stroke, is compressed in the combustion chamber during the compression stroke. and is exploded at the end of the compression stroke to impel the piston or piston-hammer forwardly to etl'ect the work ing stroke.

One object of the present invention is to provide a portable, substantially self-contained, easily handled and manually controlled tool of the impact-hammer type, with simple and etlicient means whereby the explosive mixture may be drawn into the cyl inder, compressed and transferred to the explosion chamber where it is finally compressed and exploded to forcibly impel the piston-hammer at a high speed, for the purpose of imparting a powerful percussive blow to the shank of a drill, chisel, riveting or digging tool, or the like.

A further object of my invention is to provide means for regulating or controlling the force of the impact of the piston-hammer against the tool; to provide a rotor, preferably surrounding the cylinder, for effecting the return or COII'IPI'QSSlOH stroke of the piston-hannner, and preferably at a substantially constant linear speed; and to rotate said rotor during the automatic operation of themachine at a substantially constant speed oi rotation as a result of the engagement therewith of the piston-hammer during the Serial No. 659,350.

first part, portion or fraction of the working stroke of the piston-hammer, the energy so stored in the rotor as momentum being sutlicient to effect the return or compression stroke of the piston-han'nner and maintain a substantial constant speed of rotation to the rotor.

A further object of my invention is to provide a construction wherein the pistonhammer, after moving out of engagement with the rotor, is free to move under the explosive force of the burning fuel, and may be substantially unrestrained during the latter part, hall or fraction of its working stroke whereby a heavy sharp, etl'ective blow may be imparted thereby to the tool which it substantially strikes at the end of the work ing stroke. i g

A further object of my invention is to provide construction wherein during the latter half, part, portion or fraction of: the stroke and up to substantially the moment of the impact of the piston-hammer with the tool, the piston-hammer may be freely impelled at a constantly accelerated linear speed under the explosive action of the ignited fuel, and the linear speed of said piston-hammer may be highest at or about the moment of its impact with the tool.

A further object of my invention is to provide simple and etlicient means for compressing and transferring the charge from the intake chamber to the explosion end of the cylinder.

A further object of my invention is; to

substantially provide within the cylinder three chambers, one being the explosion chamber, wherein the charge is exploded and the force of the explosion 1S imparted to the piston to effect the working stroke or blow; the second being the intake chamber, into which is drawn the explosive mixture by the thereof; (3) the regulation or control of the force of the blow that the piston-hammer imparts to the tool; and i) the clearing of the air filters or screens. The last 01' these chambers above referred to will, for convenience, be referred to as the air compression chamber.

A. further object of my invention is to prevent dust from entering the air com pression chamber and to prevent the accumulation or dust in the iilter through which the air may be conducted to the air com IJlTGtziSlOll chamber.

A further object oi my invention is to provide said air CODllI/Z'GSSlUD chamber with a regulating valve or mechanism whereby the pressure to which the air is compressed in said chamber may be varied and controlled to vary, if desired, the :torce of the impacthammer upon the tool, and to pre vent any permanent accumulatioi'i of dust in the tilt *rs or screens through which air is condtu-ied to the air compression chamber.

it further object of my invention is to provide means for rigidly mounting; the cross-head pin in the piston-liammer so that said ei-oss-lnnitl pin will not become loosened or displaced under the vibration to which the machine is subjectednvhile operating.

[at :turther object oi my invention is to provide an improved means for keeping, constantly lubricated the cam, the crosshead cooperating tl'ierewith, and the hammer head, and to prevei'it the escape of the luln-icant from the machine when the machine is inclined from a "vertical position.

it turtliier obj-ct; of my invention is to rigidly mount upon the impact tool, the means tor carrying a liquid fuel, the ignit on coil and. the condenser; and to provide the structure with means whereby a part oi the weight ot' the entire mechanism may be rested upon the leg, thigh or knee of the operator, when the device is being used in a position inclined 'i'rom the 'verti all, or is being carried by the operator from place to place.

i-i further object oi? my invention is to provide the rotor with two cams, one of which cooperates with the )lSi10ll-l1t11l'lH16? during the operation or the device to receive energy from the piston-hammer dur-- ing the working stroke and store it in the rotor as niomentinn and to impart to the pistimdiamniier its return or compression 1 the second of: which is operative to 1 the downward moveu'ient ot the piston and the transfer of: the explosive mixture to the explosion chamber in starting the autoimitie operation of the mechanism.

A tiu-ther objectof this invention is to so securely and permanently maintain all the parts in their asseu'djiled position that they are not liable to move or become disarranged, loosened or displaced under the violent vibrations to which the machine is subjected while operating.

ii further object of my invention is to provide the tool receiving end of the cylinder with a strike-pin or impact receiving men'iber freely movable, within limits, but held in the cylinder against bodily removal, and adapted to transmit the impacts received by it from the piston-hammer, to the shank oi. the tool, carried by the chuck, and to convey and deliver compressed air to the bore of the tool to remove (fletritus from the hole being drilled.

it lurther object ot' my invention is to provide means to prevent. the escape of air around the outside of the shank end of the tool, and compel such compressed air to pass into and through the tool.

l urther objects of my invention are to limit the dowmvard movement of the piston-hammcr by the engagement of the crosshead pin with the bottoms of the slots through the cylinder, before the rollers oi. the cross-head reach the lowest portion of the cam oi the rotor; to prevent the ends ot the erossdiead from contact with the lowest part oi the cam when a cavity or so'ttspot is OTHOHHtCl'Gtl in operating the drill or when the device is being carried from place to place while operating; to provide a construction wherein the ends oi the (moss-head will not be subjected to any blow or in'ipact whatever at the end oi the working stroke ot the piston hannnerg and to provide n'ieans tor absorbing a severe blow oil the pistonhammer against the strike-pin, or the parts in which the StTllliC-pill is mounted when the resistance of the material beingdrilled is lessmed itor any reason.

Further objects of my invention are to provide means with the drill structure for compressing air, and conducting it to and through the hollow bore of the tool-bit.

A 'l'urther object of my invention is to divide the cylinder by the piston-l1ammer into an GXPlOSlOH or combustion chamber located at one end of the cylinder, and two other chambers, one of said other chambers being at the other end (it the cylinder and the other being interi'i'iediate the [)lSliOll-Glld and the hammer end of the piston-hammer, one (it said two ehan'ibers being a fuel receiving or mixing chamlpier, and the other being an air ci'impression chamber.

further object of my invention to provide the air con'ipression chamber with a valve to limit the pressure to which the airtl'u-nrein may. .be compressed, andto proride means for allowing the escape of air from said ('OIDPI'GSSlOH chamber when the pressure therein is above any desired predetermined point.

Further objects of my invention are to divide the interior of the cylinder by the piston hammer into three chambers or c0mtill ]y radially extending ribs orfins 12 to provide a suitable heat-radiating surface therefor. The cylinder-head 5 is also preferably provided with a tapped opening 13 into which may be titted a spark plug 1 1-. The piston-hannner 3 comprises at one end a working or explosion pistoneportion, or pisten 15; at the other end a hannner portion, impact men'iber or hammer-hei-ul 16, and an intermediate cross'head or portion 17, within which is rigidly mounted a cross-head 18 which will be more fully described below. The working or explosion piston 15 is preterably rigidly and integrally united to said in termediate portion 17 by a substantially eylindrical piston rod 19 and the hammer-head or piston 16 is also preferably rigidly integrally united with the intermediate portion 17 by 1. connecting portion 20 preferably of considerably smaller diameter than that oil the }I)lSt 011Gl'l(l 15 or the han'nner end. it

l l ithin the bore of the cylinder 1 and close to the piston-head 15, when the latter is at. the limit of its forward or downward stroke, (as shown in Fig. 1.), I provide an intermediate cylinder-head 21 through which the piston rod 19 passes. This cylinder-head 21 preferably consists ot a pair oi semi-discs (see Figs. 5 and 7) together having an exterior diameter equal to the diameter of the bore of the cylinder and when placed together providing between them a circular hole at the center thereof to tit rather closely around the piston rod 19. They are seated upon the tapered ends 23 (see Figs. 5 and T) of a plurality of screws 24. radially 6X" tending into the bore of the cylinder beneath said members. Upon the disc thus formed is placed an annulus or disc 25 of any suitable packing material, preferably channelshaped in cross-section and upon the latter are placed two more similar semi-discs 2626 preferably arranged so that the line of separation between the two latter semi-discs is equally spaced from the line of separation between the two semi-discs 22 -22. These semi-discs 26-26 are, however. of sn'ialler di. ameter than that of the semi-discs 22. and they preferably provide a larger central opening therethrough so that the disc of packing is compressed between the outer periphery of the discs 26 or inner wall of the cylinder; between the two sets of discs; and between the inner wall ot the opening through the discs 26 and the piston rod 19. Above this upper set of semi-circnlar discs 26' are provided a plurality of screws 27 having tapered ends 28 which project through the walls of the cylinder 1. and fit over the upper face of the discs 26. In this way the lower portions 22 of the intermediate cylinder-head 21 are firmly seated on the lower pins or screws 25 and the upper portions 26 are pressed toward said lower portion to compress the packing therebeeeacai tween. The intermediate cylinder-head 21 is thus held immovable within the bore of the cylinder and any leakage of gas around the periphery thereof or between said head and the rod 19 is prevented. This intermediate cylinder-head 21is assembled around the piston rod 19 before the same is inserted into the bore of the cylinder and then is slid with the pistoirhammer into the bore of the cylinder. One set of screws 24k or 27 then inserted to form a seat for the head. The other set of screws is then inserted through the wall of the cylinder to engage the other side oi the intermediate cylinder-head 21 and thus positively rigidly hold the intermediate cylinder-head 21 in position to compress the packing therebelween and form a tight joint between the bore of the cylinder and the said cylinclerdiead 2i, and between the piston rod 19 and the cylinder head 21. in this form or embodiment oi .my inven tion, the space 29 between the piston 15 and the intermediate cylinder-head 21. constitutes the "fuel intake and mixing chan'iber ot the device, and the space between the piston 15 and the cylinder-herul 5 constitutes the explosion or expansion chamber oil? the device. On one side of the WO'l'li'lllg end of the cylinder 1, I provide a carbureter 31 which coninnmicates through a passage 32 with the chamber 29. This carlnireter is more or less diagrammatically illustrated in Fig. 1 as comm-wing a. alve member $33 normally yielding-1y held upon its seat by a spring 34: and having a fuel inlet duct 35 opening into the seat of the valve member 353 and closed by the valve member 33 when the latter is on its seat. The fuel inlet duct 35 is prefer ably in con'nnunication with the reservoir or tank 36 through a. small tube or pipe 37. \Vhen the piston 15 rises from the position shown in Fig. 1 and moves toward the cylinder-head 5, air is drawn in through the passages 38 at the bottom oi the valve 31, lifting the valve 33 oil of its seat admitting; liquid fuel through the inlet duct 35, which fuel. mixed with and carried by the air into the chamber 29 oil the cylinder. In this way an explosive mixture taken into the space or chamber 29 on the lip-stroke of the piston-hammer ton-hannner at.- the end. oi the upward or nonworking stroke is shown in Fig. 2.

The cylinder 1 is also provided with a port 1.39 which by a passae e e0 i-onnnunicates with a, port 4] on the other side of the piston 15. lVhen the piston 15 is in its lowest position the chaniiber 29 is thus put into communion... tion with the chamber 30. The chamber 30 also preferably provided with an exhaust port 42 which connnunicates by suitable pipe or conduit .2 with the atn'iosphere when the piston is at or near the end o'i its downward or workingstroke.

liy this arrangement the upward move- Ell] The position oi the pi ill) ment of the piston-hammer draws the mixture of air and fuel trom the carburetor 31 and port 3:2 into the chamber Qt) below the piston 15. On its downward stroke, the charge thus drawn into the chamber 29 is compressed until the upper end of the piston clears the ports 4:1 and 'lil whereupon the compressed explosive mixture is trans ferred from the chainlrer to the chamber 30 at the explosion or working end of the cylinder. this l'resh charge being;- (lLlltLLOtl upwardly or toward the cylinder-head 5 by the deflector it; on the head of the piston 15. This inrush ot the tresh charge serves, when the device is in operation. to expel the spent gases remaining in the chamber 30 at the end of the working stroke. After the charge has thus been transferred to the chamber 30 the piston on its upward movementcloses both ports ell and 42 and coni presses the charge in the chamber 30 be tween the piston l5 and the cylinder head 5. At the completion oi the upward stroke the charge is ignited by the spark plug Vii-l and the piston is impelled downwardly under the explosive torce oi? the burning mixture and the cycle of operation is repealed. Thus it will be apparent that the lllbtlill-lltlilllllel is lQClPl'OCillttl within the cylinder on the principle of a two-cycle internal combustion engine in so far as the intake, transfer and compression and explosion of the explosive mixture is concerned, and in so far as the expulsion of the spent charge by the incoming fresh charge is concerned. The mechanism whereby the return or non workingstroke of the piston is effected will be described below.

The working piston to may be provided with the usual piston LlllgIStt-ft. In order tha the piston to may have a relatively long bearing surface in the cylinder and yet not beunduly hear I prefer to make the worl inn piston hollow, as clearly shown in. Figs. 1, 2 and In order to render the upper end of the piston sulliciently strong and rigid to withstand the high pressure to which itis subjected by the exploding I prefer to provide the upper end thereof with a hole into which is threaded a stillening stud t5 the lower end of which is forced hard against the lower wall 46 of the chamber iii in the piston 15. In this way a relatively lightpiston may be employed, with the working end thereii t sutliciently strong to withstand the heavy pressures and shocks to which it is subjected. To prevent the stud from turning and becoming loose, by reason ot the vibration to which all the parts are subjected during the operation of the device, I prefer to lock the stud with a fr"tt!\V or stud 45 after the stud has been properly positioned in the hole in the pistonhead.

'lhe lower ends of the ribs or tins 4 on ball race at is disposed a series of antitrio tiou balls or rollers Said hall race 51 is securely seated in the upper section 53 of a hub or rotating member o-t. The lower section of the member 5% is rigidly secured to the upper section 53 by bolts 56 as clearly shown in Fig. 1. To the inside of the upper section ili'i ol the hub 54 a cam 57 is secured by bolts or screws 58 (see Fig. l.) and this cam, so attached to the upper section 53 ot the hub, is adapt-ed to be slipped over the lower end of the cylinder l with the upper hub member 53 to the po ition shown in Fig. l in assembling the device.

The intcrmeljliate portion '17 ot the piston han'imer 3 is preferably nearly but not quite as large as the diameter of the bore through the cylimler t and it is transversel v diametrically bored to receive a cross head pin L8. This cro.-"s-head pin 18 (see Fig. all is preferably provided with a cylindrical central portion so adapted to lit tightly into a cylindrical opening- 60 extending transversely through the intermediate por tion 17 ot' the piston-haminer. The central cylindrical portion 59 terminates on one side in a rectangular head 1 adapted to [it into a correspondingly shaped rectangnllar recess ordeprcssion 62 provided at one end of the transverse hole till through the portion ti' and adjacent said head (ll said cross-head pin provides two parallel t at vertical faces (33 adapted to smoothly til into the slot 2 extending longitudinally of the cylinder. 'lhcse tacos (33 are preferably provided with grooves ti-=lto t acilital'e the lubricatilm thereot. Beyond these tlat vertical laces 63 said crosshcad pin is provided with a cylindrical portion (35 of reduced diameter and upon which is mounted to turn a hardened steel oller no securely held in place by a collar 37 secured to the cross-head pin 18 by a ransverse tapered pin (38 driven through ihe collar (3? and a transverse hole at that end of the cri'iss-head pin 18. The opposite end ol' the. central cylindrical portion 59 of the cross-head pin I8 is similarly provided. with a pair ol parallel vertically disposed fiat 't'aces an adapted to lit smoothly between the parallel walls of the slot 2 onthe other side of the cylinder 1 and said faces 69 are also preferably provided with 01l grooves 69. Beyond these fiat faces 69 said crosshead pin, 18 is provided with a reduced cylindrical portion 70 upon which is mounted a hardened steel roller 71 similarly held in place by a collar 72 and a tapered pin 73 driven through said collar 72 and the end of said cross-head pin 18.

The width of the cross-head pin 18 between the parallel faces 63 is not less than the diameter of the cylindrical portion 59, so that, to assemble the device it is only neces sary to insert the piston-hammer within the bore of the cylinder and bring thehole 60 in the intermediate portion 17 into alineincnt with the slots 2 and 2 whereupon the crosshead pin may be inserted into the said hole 60 through the wide slot 2 and driven until the shoulder of the rectangular portion 61 fits into the rectangular recess at the end of the hole 60. The cross-head pin 18 is arranged to fit tightly in the opening 60 and keep said pin in proper relation thereto, with the flat faces 63 and 69 parallel to the slots 2 and 2 respectively. The hole 60 is provided with a lteyway 7 1 and the crosshead 18 with a key 75 slidable in said heyway. This preve. ts any rotation of the pin 18 within the hole 60 in driving the cross head into final position therein.

On account of the severe vibrations to which the parts are subjected when the drill is being operated, it may be desirable in someinstances to further lock the cross-head pin 18 to the piston-hammer and to do so I may provide the cross-head pin 18 with a transverse hole 59* to receive the end of screw '76 projecting into the said hole 59.

As clearly shown in Figs. 13 and 14 the intermediate portion 17 may be provided with a relatively wide slot 17 and a hole 17 tapped to receive the screw 76. A look plate or washer 1'? ts between shoulders of the slot 17 and cannot rotate on the screw 76. The washer 17 has one or more prongs 17 adapted to be bent up into one or more of the notches 1.7 in the head of the screw 76. After the cross-head pin has been driven into the hole 60 of the intermediate portion 17, and its end into the hole or recess 58 in the cross-head pin 18, as above describech and is tight in its final position, a prong 17 is bent outwardly into a notch 17 ot' the screw head. thus definitely locking the screw and preventing it and the cross-head pin 18 from becoming loose. The cylinder 1 is provided. with an opening 1 into alinement with which the head, o'f the screw 7 6 may be brought for the passage of a tool to insert or withdraw the screw 76. After the cross-head pin 18 has been thus inserted into the piston-hammer and secured thereto the lower section 55 of the hub 54, with the lower cam 77 secured therein as by screws 78 threaded into holes 78 therein, is slipped over the lower end of the cylinder mo em 1 and said lower section 55 is secured to the upper section 53 of the hub by the belts or screws 56. In the lower end of the lower section 55 otthe hub 5a is a recess '79 in which is seated an upper ball race 80 in which a series of antitriction balls or rollers 81 are adapted to track.

The exterior of the cylinder is provided with screw threads 82 over which may be threaded a flanged ring 83 which carries the lower ball race 84 adapted to coact with the under or inner side 01 the balls 1. When this flange 83 is properly adjusted, the entire hub 54- with the parts attached thereto is adapted to rotate on the balls 81 and 52 on an axis coincident with the longitudinal axis of the cylinder 1 and the longitudinal axis of the piston-hammer 3.

Beneath the flanged ring 83 and surrounding the cylinder 1 is a friction ring 85, which I is preferably of steel. and against this ring, 85 bears the inner inside bottom wall. 86 of the oil pan or lubricant reservoir 87. The inside wall oil the hole through the bottom wall of the oil pan 87 lits snugly against a smooth cylindrical surface 88 on the cylindcr 1 immediately below the screw-tlwcads 82 and a short distance below this smooth cylindrical surface 88 a threaded section 89 of slightly smaller diameter than the di-- amcter of the cylindrical surface 88. A ring; 90 of packing, material is fitted snugly against the bottom oi the oil pan 87 and neat to that is placed a nut-lock 91. )JQXt below the nut-lock 91 is a nut 92 adapted to be threaded over the threaded section 89 of the cylinder. After the flanged ring 83 has been adjusted to make a proper bearing: for the hub 54 on the balls and 81, the nut 92 is adjusted so as to tightly compress the bottom of the oil pan between the steel ring 85 and the packing ring 90 so as to make a liquid tight closure tor the bottom of the oil pan or receptacle around the out side surface of the cylinder 1. The bottom wall of the pan 8? is provided with a series of notches 93 and the upper tace oi the nut 92 is also provided with a series of similar notches 94;. The nut-loclt 91 is provided with a series of radially extending); fingers or prongs 95 and when the nut 92 has been adjusted in its final position. one or more of these prongs is bent upwardly into th notches 93 on the bottom of the pan and other of these prongljs or lingers 95 are bent downwardly to engage with notches 9-1 in the nut. In this way the nut is positively locked and heldin its adjusted position. i The hammer-head 16 is preferably pro-- vided with a series of packing rings 86 and is adapted to compress and force air under pressure through the drill-bit to the bottom of the hole being drilled for the purpose of removing" dust or detritus therefrom.

The lower end of this cylinder 1 is pro lull till

vided with an anvil 97 closely tilting the in terior walls of the cylinder and n'ovided preferably with an enlarged end, or head 98 fitting into an annular recess 99 at the end of the cylinder. This anvil 97 is preferably held in position by a tool-chuck or toolholder 100 which is held tirmly against the end of the anvil 97 and the end of the cylinderby bolts 101 passing through cars 1013 projecting radially theret'roun said bolls also passing through a. ring 103. The opening 104: through the ring 103 is preferably slightly larger than the external flange 1053 at the end of the cylinder so that the ring 103 may be readily passed over said tlange. Between said ring 103 and the tlange 10?) is interposed a split ring 106 titting against the upper shoulder of the flange and having 'its upper face 107 inclinedand titted against a correspondingly inclined surface 108 on the ring 103. At'ter passing through the ring 103. the bolts 101 are surrounded by coil springs 109. the compressive force of which maybe adjusted by the nuts 110 on the ends of the bolts 101. Vhen so assene bled the springs hold the tool-chuck squarely against the end of the cylinder, the head 98 of the anvil. 97 against the bottom wall of the recess 99 and the split ring 106 lirmly against the out-side of the cylinder 1 and against the upper sur't'ace ot the tlauge 105.

The anvil 97 is provided with an opening 111 circular in cross-section, extending coaxially therethrough and in this opening is slidingly fitted the strike pin 112. The opening 111 is of larger diameter at its lower end than at its upper end to provide a shoulder 111 relatively near the lower end of the anvil, and the strike-pin 112 is provided with a flange or head 11?) which is adapted to tit against the said shoulder 111". The head or flange 113 smoothly tits within the larger end of the opening 111 and the body oi the strike-pin smoothly [its within the smaller diameter of the opening 111 through the anvil. The length of the strikc. pin such that when the head or flange 113 is seated against the shoulder 111-H the upper end of the strike-pin projects slightly above the inner face of tl. anvil 97 so as to receive the blow delivered by the pistonhammer when the hammer head 16 strikes the upper end of the strike-pin 112.

The extent to which the strike-pin 1152 is made to project above'the top of the anvil 97 may vary and depends upon the nature of the work for which the device is to be used. Generally speaking. the strike-pin should. project above the anvil a distance substantially equal to the. greatest distance that the tool will normally advance under a single blow in. drilling or cutting a given material. but in drilling rock and other ma terials, soft spots or cavities are. frequently encountered by the drill with the result that the drill will advance an abnormally great distance under an impact of the hammer. \Vhen this occurs, the hammer-head 16 will. impinge against the top of the anvil 97 and the blow thereupon will generally be absorbed by the springs 109.

in this cl'llliOdlHlCllll of my invention. the strike-pin provided with a small bore 1H extending longitudinally therethrough tor the purpose of delivering compressed air to the toolbitheld in the lool-chuck 100 as will be more fully (jlescribed below.

The chuck or tool holder 100 is preferably provided with an axially disposed hole 115 therethrough. preferably hexagonal in shape to tit loosely around the hexagonal or correspondingly shaped upper end 01'' the toolbit 116. The length of the chuck 100 is a little less than the length of the end 116 of the tool-bit so that when the. tool-bit is inserted in the chuck. the upper end thereoi will bear squarely against the low r end of the strike-pin 112 holding the head 1.13 lhereol l'irmly against the seat in the anvil 97 with the upper end of the sl'rikcpiu 1113 projecting slightly above the inner face of the anvil 97 and in the path ol the hammerhead or piston to when the piston-hammer is near thecnd ot its working stroke.

The drill-bit is prelerably provided with the usual collar 118 and the chuck 100 is preferably provided with a yoke 110, the. arms of which are, pivoted at their ends on the studs 120 to the chuck 100. This yoke 119 preferably has a semicircular recess or opening 121 between the arms of the yoke adapted to loosely tit around the upper cud ot the drill bit 117 a short distance below the collar 118 to preventthe tool-bit t'rom slipping out ol the chuck when the nn chai'iism is lifted. The semicircular recess or opening 119 is kept pre-sed agaii'ist the upper end ot the drill-bit l by a pair of spr ngs 132, 122. the lower ends of which may be respcc-- tively hooked over projections or studs 1233 on the yoke 119 and the upper ends o't which may be respectively attached to pins or studs 112i rigidly mounted on the chuck 100. This construction is clearly illu trated in Fig 1 and .2. The tool-bit 117 is preferably provided with a longitudinal bore L5 extending the tall length thereof. with the upper end of said bore in alinement with the bore 11 1: through the strike-pin 112 when the parts are in the position shown in Figs. 1 and 2.

As above pointed out, the hub 5 1 consists oi two sections. h upp r section which carries the upper cam 57 and the lower section to which is secured the cam 77. these sections being held together by the bolts 56 when the parts are assembled as :bove described. Rigidly secured to the upper sect on 5:; ol the hub 5 are outwardly extending spokes 126 which carry a rim 127. In

this way the hub 54, thr s Jokes 126 and rim l2? and parts arried thereby constitute a bah'znce or momentum wheel. or rotor which is kept rotating during the ope 'ation ol the iilerice. by the engagement ot' the pistonhannner with the rain it during a part of the downwa 'd or working stroke ot the pist i'i-hannner and in which is stored energy therein sutiieient to cli'cct the return or compr ass-ion stroke oi the pistoirhannner 3. This rotatiwe movement is eti ected by the coaction ot the cross-head pin ltl with the rain 77. in Fig. 9 is shown a plane (level-opulent oi both earn. and the d i'e z'ent positions ol. the roll-- crs tilt and ill ot the r'i'ossdiead pin l8 with respect thereto throughout one complete cycle of ope 'ation.

it will be. ohsi-n'red that the cams 57 and are respectively duplex in character, that is to say; each cam is repeated at diainetrh rally opposite sides oi; t .e circle with 02(- actly the same outline or contour so that the, rollers {36 and 71 siinnltaiieonsly engage like portions oil. the cam, on opposite sides oi. the axis of the 1iistoirhainnier. The lower cain '7? is the only cain which operative during the autoniatic operation ot the device, the cznn FT being mainly tor the purpose of starting the automatic one'ation as will be reiterred to again below,

in reterring to this Fig. i), it must be rei'neinbered that; the movement ot the crosshead pin 18 is a vertical reciprocation, the flat surll aces 63 and 69 of: the cross-head pin it; traveling respectively in the slots 2, 2 of the cylinder andv by this ei'ig 'agenient ot the cross-head pin 18 with the slots 2 and 2 in the cylinder, rotative movement oi the piston-hainnier about its longitudinal axis is of cinirse prevented. At the beginning of the working stroke of the piston-han'in'ier, the rollers 36 and Tl. will be. on the high points (i of the won 7?. From these points i the portions 7) of the cam 77 ll'lCllllQS sl'iarply downwardly to points 6. Fron'i the points the portionrs (Z of the :am drop substantially vertically so that troni the points (Z to the end of the working: stroke the rollers 66 or Tl are c nnpletely out ot contactwith the rain 'i'l. :ihirino; this portion oi": the stroke the piston-haininer tree to be impelled by the explosion at a constai'itly increasing" speed up to the inon ent of impact against he strike-pin. The downward movement of he piston-haininer will be arre; ed by the inpact ot the head l6 with the strike-pin or with the anvil. or by the engagement oi the erossdiead pin, with the ends of the slots .3. it bclore the lower periphery of the rollreach the bottom surface 0 of the earn 7?. ri'hen the rollers (iii and 71 of the cross-head travel downwardly in engagement with :e sharply inclined surfaces Z), 7), they force he cain T7 and the parts carried thereby 0 rotate in the direction of the arrow 128 i. t. i

ti u

Q'Ml' nciit with tie camv After the piston-hannner strikes the strike-p111, the eontnnud rotation of the rotor. by the moinentnni. brings the upwardly inclined portions 7 of the lower :am 'i'? into engagement siinnltaneously with the rollers (36 and Tl. and the energy stored in the balance or inomention wheel will li'tt the rollers 66 and 71 and the piston-hainlner rigid. themwith rer ticaily back to the high points di -(Z of the earn 7'? and thus ellects the compressioi'i f-iti'oke oi the engine. The hub 54: with the nuns 57 and 77, andv symkes 126 and riin 127 carried l'l'iercby, thus torn: a rotor which is put into rotation by the pistonshannner during; the first part, portion or traction oii the downward or working stroke thereof; that.

is to say. when the rollers 66 and Tl. are torred tlflilifllStl the inclined poritions b-b of the cam 7? suificient energy is stored to etl' ect the return or compression stroke ot the piston-hi nnner. The angle which the surface 7) wakes with the verii :al passing through the ighest point o of the s irilace oi the cam 77 s a small one as tor instance, and after the rollers as and "fl. pass over the point 0 the piston-han'nner inoves very rapidly to the end of its downward stroke, into engagement with the strike-pin 112. The piston hammer is out of engagement with the cam 77 during}; this latter part oi. the stroke and is free to be impelled at a constantly increasing and high rate of speed under the explosive torce ot the burning gases in the coinlnistion chamber 30 during this section or latter half of its stroke. The rotative movement oi the cam 77 during the working stroke of the piston-han'ii'ner may be indicated by the distance 72/ in. Fig. 9 which may be and is relatively small as con'ipared with the distance i tln'oneh which the cam rotates during the return or compression stroke of the piston. Thus it is that a relatively long slow rise may be given to theportion of the earn 7'? in order to impose as little work as possible upon the rotor in effecting the return stroke ol the piston-haminer and the compression of the explosive, charge in the er-zplosion clnin'iber. The contour or shape of the portion f oi the rain 7? may, however, be considerably aricd without departing, from the spirit and scope of my invention as will be relierred to again below.

in order to start. an internal conil'nistion engine, the piston must he reci n'ocated within the cylinder to draw an explosive mixture into a niixinc chamber: to trans'ter it to the rzplosion chamber and to there connircss it prior to the ignition thereof and in the present device, the cam I)? for that pnrpose. The portion oi the can: 57 is preterably vertically spaced above the high lit) - the device.

point a of the cam 77 by a distance substantially equal to the diameter of the rollers 66 0r-71. A slight clearance is allowed at this point (as clearly indicated in Fig. 9). From the point j the cam surface is inclines downwardly diverging slightly from the portion 7) of the surface of the cam 77 and extending to the point Z. From this point a portion m of the cam may rise in any predetermined manner and then extend to the point j on the other side of the cam. The surface is of the cam 57 is the only surface thereof which is really operative and then only in starting the automatic operation of Assuming the piston-hammer 3 to be in its lowest position, the manual rotation of the rotor of the device will bring the surface 7 of the cam 77 against the rollers 66 and 71 and will lift the piston-harm mer moving it upwardly toward the cylinder head 5 and drawing an explosive mixture into the mixing chamber 29. The continued, manual rotation of the rotor will then bring the surface of the cam 57 into engagement with the rollers 66 and 71 and this engagement will then move the piston-hammer downwardly to compress the explosive charge in the mixing chamber 29. lVhen the rollers reach the point Z of the cam 57, the port 41 will be open and the explosive charge will be transferred from the mixing chamber 29 to the explosion chamber 30. The continued rotation of the rotor will now bring the inclined surfaces f of the cam 77 again into engagement with the rollers 66 and 71 to compress the explosive charge in the explosion chamber 30 and to draw a new charge into the mixing chamber 29. As the rollers 66 and 71 now roll over the high points a, of the cam 77, the explosive charge in the chamber 30 will be ignited and the automatic operation of the device will continue so long as fuel is supplied thereto. Thus it will be seen that the only operative portion of the cam 57 is the portion In which effects the initial compression of the explosive charge chamber and to effeet the transference of it to the explosion chamber. Theoretically, during the automatic operation of the device, the rollers 66 and 71 would not engage the upper cam 57.

In the embodiment of my invention shown in Figs. 1. 2 and 3 1' provide, in addition to the chambers 29 and 30, a third chamber, 129, which is located between the piston-head 16 and the anvil 97. The hammer-head 16 reciprocating in said chamber 129 performs the double purpose of imparting a blow to the drill-bit and for compressing air which in turn may be employed to perform several functions, namely, to remove detritus or dust from the bottom or hole; for regulating and controlling the force of the blow with which the pistonhammer strikes the strike pm .12 cooling the explosion end of the cylinder, and for clearing or cleaning the air filters, referred to again below. At the bottom of the chamber 129 is an air inlet port 130 controlled by a check valve 1'31, 00- acting with its seat 132, allowing air to be drawn through the pipe or passage .133 into the chamber 129 upon the upward movement of the hammer-head 16 but preventing any passage of air from said chamber 129 into said pipe or passage 133. The upper end of the pipe 133 communicates with .a chamber 134 formed in the wall of the oil pan 87 and the upper end of said pipe or passage 138 extends laterally through the wall of said pan 87 and is provided with an air filter or strainer 135.

For the purpose of driving air down through the bore of the drill to remove the dust and small particles from the bottom of the hole being drilled, the upward movement of the hammer-head 16 draws air from the outside atmosphere in through the filter 135, chamber or passage 134, pipe 133, past the check-valve 131 into the chamber 129 and the downward movement of the hammerhead forces the air so drawn into the chamber 129 down through the bore 114 in the strike-pin and through the bore 125, through the tool-bit 117 to the bottom of the hole.

For the purpose of regulating the force of the blow imparted to the strike-pin 112 and through it to the tool-bit 117, I provide a port 136 also communicating with the bottom of the chamber 129 through the wall of the cylinder 1. This port 136 by a pipe or passage 137 communicates with a chamber 138 in a pressure controlling valve 139. This valve may comprise a movable valve member 140 adapted to be normally held seated against the valve seat 141 by a spring 142 compressed between a piston-head 143 and a cap 144 closing the lower end of the cylinder 145. The valve member 140 is provided with a stem 146 extending longitudinally through the cap 144 and the outer end of said stem 146 is preferably provided with an adjusting member 147 having radial arms or wings 148 adapted to ride or slide over a pair of arc-shaped cams 149 slowly rising from the underside of the cap 144 and which may be provided with suitable notches 150 for the purpose of retaining the wings or arms in any adjusted position with respect thereto. By turning the member 147, the pressure with which the valve member 140 presses against the valve seat 141 may be delicately adjusted.

The diameter of the piston-head 143 is considerably larger than the diameter of the valve seat 141. The ratio of the area of the piston-head 143 to the area of the valve seat 141 and the pressure of the springs 142 may be so proportioned that until the pressure of the compressed air under the hammerhead 1e and in the chamber 121. a prede termined point, the valve member 140 will remain seated on the valve seat 1 1-1 and up to that pressure substantially all the air being COHLPYGSSGKl in the chamber 129 may be forced down through the bore 11%- of the strike-pin orup to any other point to which air from the compression. chamber 129 may be desired, but when the pressure in said chamber rises above that predetermined point, then the piston 1-13 will be forced downwardly to lift the valve member 1410 d its seat, and to permit the air to escape into the passage 151 and thence through a passage 152 termed in the wall of the lubrieatingoil pan 8'7 back into the inlet chamber or passage 134.

This discharge 01' air from the pressure controlling valve 139 back into the chamber 134 is tor a very useful purpose. it will be appreciated that in rapidly drilling; rock and blowing the detritus from the hole being drilled fast as the same is formed will, in many instances, cause the air surrounding the mechanism to be tilled with line dust. T 0 take air commingled with this dust back into the chamber 12901 the drill would be likely to injure the mechanirzxm. It would tend to cause the parts to wear very rapidly. The air filter 135. is to prevent this dust from being drawn in the chamber 129, but under these circumstances the accumulation oil? the dust in the filter 135 would be considerable and under ordinary circumstances would necessitate'a frequent replacement of the filtercloths or wires used in the filter to arrest the dust. When, therefore the controllingvalve is so adjusted as to lift the valve 1410 on its seat at or near the end of the downward stroke of the hamnierdiead, air at the high pressure then existing in the chamber 129 will be driven through the conduit or passage 151 into the chamber 18-1 and out through the filter 135. This sudden pull of air under highpressure occurring at the end of the compression stroke will blow the dust accumulating on the outer sides of the filter cloths or wires 135 oiiitwardly and oil of the same thus keeping them clear of any considerable accumulation of dust tor a long time. It is believed that "from the above, the operation of this portion of the apparatus will be clear. The upward stroke of the hammer-piston 16 draws air through the filter and the dust collects on the outside of the filter cloths or wires. At the end of the compression stroke air at high pressure is forced in the reverse direction through these filter cloths and clears the filter cloths otthe filter 135 of the dirt accumulating thereon. In some instances the valve may be adjusted so that it is just oft its seat so that some air will pass therethrough throughout the working strokef It may be desirableto use some of'the air compressed in the chamber 129 to cool the cylinder head 5. For this purpose I may provide the chamber 125) with another port 153 (see Fig. to which is attached a pipe 154 which may be passed through suitable openings extending through the threaded projections l and 1 on the surface of the cylinder 1. The upper end 01 the pipe may be provided with a valve 155 adapted to open and close the passage through said pipe 151i. When said valve 155 is opened air from the chan'iber 129 may pass upwardly through the valve 155 through the pipe 156, the upper end 157 of which is down turned to discharge the air against the top side of the cylinder head 5. Any suitable coupling 15? may be provided between the pipes 15% and 156 to provide for the convenient removal of the pipe 156 when its presence is not necessary or desirable.

By the above provisions the force with which the hammer-head 16 impinges against the strike-pin 11.2 may be nicely adjusted, that is to say the pressure produced in the chamber 129 near the end of the stroke may be made sutlicicnt to diminish, when so desired, the force 01 the blow with which the strike-pin is struck by the hammer 16. This operation may be of considerable assistance in starting the device when the end of the tool may not be in engagement with the rock to be drilled or in seating the drill to begin the drilling operation when the full force of the blow might not be needed or desirable.

The tank or fuel reservoir 36 is preferably supported between and on a pair of still tubular supports 159, the upper ends of which are bolted or otherwise rigidly secured to lugs 160-160 rigid with the cylinderhead and which may extend rearwardly and downwardly from the sleeves 10 on the cylinder-head The lower ends of the supports 159 may be provided with slots 1 5) which lit over the'opposite ends. respectivel ot a stud 161 rigidly secured to the lug 161 extending radially from the ring: 103. he clearly shown in Fig. 2. this tank 36 may be hung on said tubular supports 159 by st raps or brackets 162-162 secured to the opposite sides oi the tank 36. 'lhetop oi the tank 36 may be provided with a suitable pocltet or recess 1.63 adapted to contain an induction coil 1641 and a condenr er 165 of the ignition system (see Figs. 2 and 11 1n the construction illustrated in Figs. 1 and 2 fuel supplied from the tank .;(3 t the carlfiureter 31 by an aircompresor 1.66 which may be mounted in the tank. l i hen the knob 16'!- is drawn up by hand to ele ate the piston 168 the check valve 169 remains closed and air passes through the flexible packing 170 surrounding the piston 168. When the knob is depressed air enters the cylinder above the piston 168 tl'irough the longitudinally till lull

lib)

port 172 and the air trapped in the lower end of the cylinder is forced through the check valve 169 into the tank 315 where it creates a pressure above the level of the liquid fuel therein, to force the fuel through the tube 37 to the carburetor, the pressure in the tank 86 being registered on a pressure gage 173. In the rear of the tank 36, the two tubular supports 159 may be rigidly connected together by a crossbar 1T1 upon which may be pivoted, in any suitable manner, a sheet metal guard or plate 175, the lower end 17 6 of which may be transversely curved to fit against the thigh or leg of one operating the drill. In this way a substantial part of the weight of the drill may be supported on the leg of the operator when a hole is being drilled at an angle to the perpendicular. This pivoted plate 175 will turn on the rod 17st and adjust itself to the leg of the operative and assist him in steadily supporting the device in any desiredinclined position, and in carryingthe device from one place to another.

Referring now more particularly to Figs. 2 and 11, on the bottom of the tank 36 is prciferably secured a block 177 of insulating material carrying two binding po -ts 178 and 179 to which the opposite ends of a battery 180 may be attached by leads 181., 182 respectively. The binding post 1T9 is preferably grounded to the machine by a wire 193. The other binding post may be connected by a wire 181 with binding post 185 which in turn may be connected to one terminal of the primary winding 186 of the induction coil 161. The. other end of the primary winding 186 may connect with a binding post 187 to which may be connected a wire 188 leading to the binding post 189 of an insulated block 190 of the contact device 191. This contact device may be of any suitable construction but the one I prefer to use comprises a longitudinally adjustably lined contact point 193 and a n'iovalgile contact point 193 cooperating therewith and intermittently engaging said fixed contact point when the projections 191- of the plates 195. n'iountcd at diamctrically opposite points on and carried by the spokes 126 of the rotor travel under and engage and lift the movable contact 193. The movable contact point 193 is normally kept in its lowermost position and out of contact with. the fixed contact by a. coiled spring 1% as clearly shown in Fig. 11. These contact points are preferably carried or mounted in a housing or casing 197 preferably rigidly secured to a longitudinal slidable rod 198 mounted in bearings 199 at opposite ends of a radial slot or cut away portion 200 in the rim of the hood or cover 19. By a slight adjustment of the contact device 191 forwardly or back 'ardly, the spark in the explosion cylinder may be advanced or retarded.

One side of the condenser 165 which, as

above stated, is preferably mounted in the recess 163 of the tank or reservoir 36, may be connected to binding post 201 and thence by wire 202 to the wire 188. The other side of the condenser 165 is preferably grounded to the machine, by any suitable clmnection, 203. In this way the make and break contact points 192 and 193 are bridged by the condenser 165.

The secondary circuit of the ignition system comprises the secondary winding 201, one end of which may be connected to binding post 205 and thence by wire 206 to the spark plug 1% which is grounded to the machine in any suitable manner. The other end of the secondary winding 204 may be grounded to the machine by a suitable connection .207;

Any suitable means for supplying a suit able amount of lubricant to the cams, crosshead. and lower piston or hammer piston may be employed but in Figs. 1, 2 and 8 I.

have illustrated one constructii'm wherein the lower section of the hub 5-1 may be provided with inclined tubes i208 extending thercthrough with the lower ends 209 thereof projecting forwardly in the direction of the rotation of the rotor. As the rotor revolves relatively rapidly, oil will be forced upwardly through the inclined tubes 208 and will be discharged in a stream directed againstthe engaging surfaces of the cams 57 and 77, and against all of the interior of the upper section 58 of the hub 5 1. The pan 8? will normally contain a suitable amount of oil and the packing rings 85 and 90 are for retaining the oil in the pan. In this way the piston rod 19, the cross-howl pin, the cams and the roller bearings of the rotor are kept thoroughly lubricated. An oil. duct 210 may also be provided to permit the oil thrown over the upper edge of the cam 57, over the balls 52 and between the ball races 54) and 51. and outwardly over the ball race 51. to fall back into the pan or tank 87.

There will be no special need of any packing rings around the strike-pin 112 or around the anvil .17. because the oil which works past the hammer head lli into the chamber 12.) will form an oil seal between the walls of the cylinder 1 and the anvil and between the anvil and the strike-pin 112. The over-hanging inner top wall 211 of the pan ST is for the purpose of preventing the oil from running out ovcr thc top of the pan when the tool is placed in an inclined position. \Vith this couslruw tion the drill may even he inverted without spilling oil from the pan 8T.

YVhen the machine has been once set in motion by manually rotating the rim 12" of the rotor until the first explosion takes place in the explosion chamber 30, the piston-hammer will be reciprocated on the principle of a two-cycle single-acting explosion engine. Gn the down stroke the explosive mixture I it) will be compressed in the chamber 29. the

cross-head pin will lirst traverse the por tions b-b ot the lower cam 77 and then it will complete the downward stroke entirely out of contact with the cam 77. it the end of its stroke, the hammer-head of the pistonhainm-er will engage the projecting end of the strike-pin 112 and impart a blow to the tool-bit 117. On its down stroke the air contained in the chamber 125) will be compresscd and driven down the port or hol 11 1 in the strike-pin and thence through the bore on. the tool-bit to the bottom of the hole being drilled and will torcibly eject the small chips or detritus from the hole leaving the bottom of it clear tor the en gagenient therewith ot the torn-hit. ill at or near the end of the downward or working stroke the pres ure oi? the air in the chainber 129 be greater than a predetermined. pressure to which the valve 139 has been set,

i this pressure controllingvalve 139 will allow the excess air to pass out through the waive seat 141 and the passages 151 and 160 to the chamber 13 1 whence it will p :48 outwardly through the filter 135 removing the dust which may have collected on the outside or the filter plates or screens 12.35 therein.

After the cross-head pin 18 has left the surfaces 7P4; of cam 7? the rotor continues to rotate by momentum and brings the op posite inclined portions f*/ of the cam 'i"? into simultaneous engagement *ith the rollers 66 and 71 respectively on the cross-head pin and will lift the piston-hamn'ier to e'ltect the return or (fOlIlPYGSE-llOll stroke at the pis ton-hammcr. This upward movcinent ot the piston-hammer will draw air into the rhana her 12 through the tilt-er 135, chamber 12-31, conduit 32-3 and. past the checli valve 11313. it being understood that as soon as the pressure in the chamber 1%) drops to a point lower than the predetermined prcsearre for which the valvev 1.39 is set the valve i l-E2 inn mediately closes on its seat 1 11 and air can no longer pass through the pressure control valve 139.

In Fig. 15 is illustrated a modified construction for conducting the compressed air from the chamber 129 and conductingit to the tool-bit 117. Insteadv o1 providing; the strike-pin with an axially arranged bore e:-:- tending therethroue'h, as in the previously described en'ibodinient of my invention. the strike-pin 112 is substantially solid except that it may be provided with a short hole 212 at the lo ver end thereof wl'iich cons municates through a radial passage 213 with an annular recess 21 1 in. the outside thereof forming; a small chamber; when the strikepin is positioned in the anvil 97. The anvil 97 is provided with a radial passage 215 which communicates with the chamber 214; at its inner end and registers at its outer end with a similar passage 216 through the wall of the cylinder. The outer end of the passage 216 communicates through a pipe 217 with a check valve 218, of any approved type, and the other side of the check valve is connected by a pipe 219 with a passage 220 passing through the walls of the cylinder into the compression chamber 1 9 just above the inner end of the anvil 9?. In this way the air com )lQSSQCl under the han11- mer-hea d 16 in the compression chamber 129 passes out through the port 220 and by and through the check-valve to the channel EZt-Jl and thence to the bore of tool-bit 117. The width ot' the channel 214 is such that when the strilze pin advances in the anvil under the blo Y iu'iparted thereto bv the pis ton-hai'nuier the hole or port 21:). through the anvil 9 will not be closed or cut oil", and air will be free to continuously {low into the here or tool-bit throughout the working stroke of the pist ni-hainmer.

In Fig.1. 16 is illustrated a slightly modified co" struction wherein the fuel mixing chamber is located between the hammer-head and the anvil at the lower end of the cylinder 1 and the air compression chamber is located between the workingnpiston section of the pist m-hammer and the intermediate cylin der head. The mixinc chamber 29 communicates through a port 32 with the carbureter Also communicating with the mix- Eng chamber 29 is a port 39 which communicates through the transfer passage 40 with the inlet 11 leading into the combustion chan'iber 30 when the piston 15 is at. or near the end of its downward working stroke. This transfer passage 4-0 consists in this instance of a pipe passing through the flanges if and 1" on the outside, of the cylinder 1.. in this instance these flanges or rines are made all a little larger than that used in the construction previously described tor the purpose of providingample space for the passage of this tube or pipe 40 therethrough. The carbru'eter 31 communicates with the bottom of the tank 36 by a pipe 37' through which fuel may be conducted by gravity to the carlmreter. The air compression chamber 129 is beneath the working piston 15. An air inlet port 131. is in comn'iunicatiou with this chamber 129 and the passage of air therethrouggh is controlled by a. check-valve 1.32. Also in cominruiication with the chamber 129 is an air outlet port 220 which by a. pipe or passae e 219 communicates with a check-valve 218 near the lower end of the cylinder. lhis pipe 219 also preferably passes through the enlarged flanges 1 1 on the outside oi the cylinder and between the main portion or body of the cylinder and the rotor mounted around the cylinder. Below the check-valve 218 the compressed air from the chamber 129 is conducted to the tool-bit in the same manner as described connection with m;

too

that is to say, through the pipe 217, passage 216 through the cylinder walls, through passage 215 through the anvil 97, and thence through the chamber 214 and the passage 213 with the short bore 212 in the end of the strike-pin 112.

In Fig. 16 .l have also shown another slight change in construction. The bore through the cylinder 1 in this instance is not of uniform diameter throughout substantially the whole length of the cylinder, for I provide a. seat or shoulder 21 therein upon which the intermediate cylinder-head 21 is seated. In this form of my invention the intermediate cylinder-head 21. which in construction is like that in Fig. 7, is held firmly against said seat 2 1 and the parts thereof are held firmly together by the upper screws 27 in the manner heretofore described.

- It will thus be seen that the two types of construction as illustrated in Figs. 1 and 2, and in Fig. 16 each have advantages. In the construction of Figs. 1 and 2. the fuel mixing chamber is immediately beneath the working piston 15 and the transfer passage from the mixing chamber 29 to the combustion chamber 30 is short. In said construction the air compression chamber is situated closely adjacent the upper end of the toolbit so that the air compressed therein may be readily discharged directly through the strike-pin to the upper end of the tool-bit. The advantages of these features of construction must be obvious.

But, on the other hand, in the construction ilhrtrated in Fig. 16 the carbureter is located at the lower end of the cylinder so that the fuel from the tank 36 may readily flow by gravity through the pipe 37 thereto, thus dispensing with the air pump for forcing all the fuel in the tank to the carbureter. This advantage of this construction is now also apparent.

I have found that it may be advisable to provide special means for insuring the passage of the compressed air from the strikepin to the interior bore 125 of the tool 117. 'lhis may be accomplished by enlarging the upper end of the hole 115 through the tool holder or chuck 100 and seating therein a packing washer 221 having a central flange or projection 222 which fits against the outside of the shank 116 of the tool 117 and surrounding this flange is a tight ring 223 which compresses the flat portion of the packing between the lower end of the anvil and the bottom of the recess in the toolholder 100 and also presses the flange 222 tightly against the shank of the tool. If the shank of the tool be hexagonal in shape in crosssection, then the flange 2242 of the packing washer should be hexagonal to snugly bear against the flat sides of the shank and the ring 223 may also have a corresponding hexagonal hole therethrough. If the shank of the too] be circular or any other shape in cross-section, the packing may be made to fit and correspond thereto. This construction prevents the air discharged from the strike-pin from leaking out through the toolholder or chuck 100 around the upper end lie of the tool and insures the conveying of the compressed air down into and through the bore 125 of the tool to the bottom of the hole being drilled.

I also find it advisable to so construct, arrange and proportion the parts that the rollers (in and Ti will be prevented from actual contact with the cam 77 at the end of the downward or working stroke. 66 and 71 are located at quite a distance from the exterior surface of the intermediate portion 17 of the piston-hammer and if these rollers were allowed to strike the cams a hard blow the cross-head pin 18 might become bent or sprung or loosened and the rollers and am might be flattened or even broken, all of which would be detrimental to the successful operation and construction of the machine. 1 therefore prefer to so position the slots and 2 through the cylinder 1 that the lower ends thereof may beengaged by the cross-head pin close to the 6K- terior surface of the intermediate portion 17 when the force of the impact of the pistonhammer on the strike-pin and anvil is so great that it cannot be or is not absorbed by the springs 109. The lower cylindrical surface of the portion of the cross-head pin 18, immediately under the flattened portion 69 thereof, is therefore arranged to engage at the end of an abnormally long working stroke with the bottom of the slot 2 and the flatunderside of the cross-head pin 18'immediately under the flattened side surfaces 63 thereof is also arranged to simultaneously engage with the flat lower surface of the slot 2. The reason for the above construction must be plain. Every stroke of the piston-hammer should cause the tool to penetrate into the material being drilled or bored. But in drilling, a soft spot or cavity might be encountered by the cutting edges of the tool or the entire drill might be lifted while running and the blow on the strike-pin might force the tool far below the upper surface of the anvil. In such' an event, a substantial part of the impact on the piston-hammer would be received by the anvil 97 but if this blow were a heavy blow, the springs 109 might not absorb all of the energy of the blow so imparted to the anvil and the rollers might strike on the bottom part c of the cams 77 were it not for the fact that I so position the cross-head pin and the slots 2 and '2 thatthe cross-head pinwill strike the lower ends of the slots 2 and 2* be fore the rollers 66 and 71 can ever reach the bottom of the cam 77. In other words, when The rollers the cross-head pin is in engagement with the lower surfaces of the slots 2 and 2 there will always be a slight clearance between the rollers 66 and 71 and the surface e of the cam 77.

In the embodiment oi my invention illustrated in Figs. 15 and 16 the anvil 97 is prevented from rotating within the cylinder order to maintain the passage 21:? in reg tration with the passage 5216. For this purpose I may provide the enlarged lower head of the anvil with a rigid pin 22% projecting radially a short distance beyond the periphery of the head into a short vertical slot 225 in the end of the cylinder. The anvil thus tree to move slightly longitudinally, when struck by the piston-hammer, but is restrained from rotative movement.

From the 'iiore oing it will be plain that I have provided a structure wherein the cylinder is divided by the piston-hammer into three compartments, namely, the combustion or explosion chamber 30, the fuel intake and mixing chamber :29 and the air compression chamber 129, all 0t substantially the same length, and. of nearly the same cz'rpacity and providing small clearances for p rts of the piston-hammer (to-acting therewith. As a result of this, substantially all of the fuel drawn in the chamber 29 on the non-working stroke is transferred at a relatively high pressure to the explosion chamber at or near the end of the work" ing stroke of the piston-hannner, the explosion chamber is completely cleared of the products of combustion of the previous working stroke and filled with a clean e2;- plosive mixture, and substantially all of the air is expelled at a relatively high pressure from the air compression chamber 30 on each working stroke of the piston-l1ammer.

In the form of my invention shown in Figs. 1 and 2, the actual capacity or full vol: ume of the t ansier chamber 29 and passage d0 may be even less than that of the explosion chamber 30, because of the presence oi? the piston rod 3 in the chamber 29, but the capacity or full volume of the air compressionchamber 29 is substantially the same as that of the explosion chamber 30.

In the term of my invention shown in Fig. 16, however, the converse may apply for the capacity of the transfer chamber 29 and the passage 10 is substantially equal to that of the explosion chamber 30, although the diameter 01'? the chamber :29 may be slightly less than that of the explosion chamber 30, and the capacity of the air compression chamber 129 may be smaller than the capacity of the explosion chamber 80, be cause of the presence of the piston rod therein. These differences are slight, however, andmay be substantially equalized or varied by the clearances and volumes of the passages leading to and from these cnambers, and the diameters of the bore in the cylinder.

This construction makes possible the transfer ct fuel from the fuel intake and. transfer chamber to the explosion chamber at a much higher pressure and velocity than can. be attained in any of the ordinary twocycle explosion engines, and to transfer to the @XPiOSlOll chamber on each Working stroke of the piston, substantially all of the contained in the "fuel intake and chamber, an ()Qtltltlflll impossible of attainment in any other form or type of two-cycle explosion engine of which I am aware. "i also makes it possible to so compres air therein that the compressed air may be conveyed to the bottom of the hole being drilled as a series of pulls or pulsations, at relatively high pressure and velocity, to ettcctively remove detritus from the bottom oi the hole being drilled, for keeping the bottom ot the hole clean for the cutting ac-' tion of the drill.

ll hil l have d-z-rscribed with some particularity the details oi several forms of my invention, 1 do not wish my invention to be coii,--;trued limited to the exact constructions shown, since many changes may be made thereii'i without departing from the spirit and scope or my invention as set forth in the appended claims.

Ha, ing thus described my invention What l claim and desire to protect by Letters Patent of the United States is:

1. in an impact tool the combination of a a nder, a piston-hammer reciproeable therein on the principle of an internal combustion engine, said piston-hammer forming with the cylinder a chamber in said cylinder into whicn air is drawn by said pis :5-llttl11l1'l81 during the return or com PI'GSM"E1 stroke of said piston-hammer and in v i ch chamber said air is compressed by said piston-hannner during the power strolre 01 said piston-hammer and means to conduct some of the air, so compressed, from said cylinder, on every power stroke of said piston-hannncr, to the bottom oi the hole being drilled to remove detritus therefrom.

2. ln an impact tool, the combination of a cylinder, a piston-hammer reciprocable therein on th. principle of an internal combustion engine, said. piston han'imer forming with. the cylinder a chamber in said cylinder into which air is drawn by said pistonhanr nicr during the return stroke of said pistonliainmcr and in which chamber air is compressed in said cylinder by said piston-hammer during the power stroke of said pistonhammer, and means to conduct some of the therein on the principle of an internal combustion engine, said piston-hammer forming with said cylinder a chamber in said cylinder into which air is drawn by said pistonhammer during the return stroke of said piston-hannner and in which chamber air is compressed by said piston-hammer during the working stroke of said piston-hammer, means to conduct some of the air so compressed to the bottom of the hole being drilled to remove detritus therefrom, and means to conduct some of the air from said chamber to the combustion end of said cylinder to cool said end of said cylinder.

a In an'impact tool, the. combination of a cylinder, a piston-hammer reciprocable therein on the principle of an internal combnstion engine, an air filter, said pistonhammer cooperating with said cylinder to draw air inwardly through said filter into a portion of said cylinder during the return stroke oti said pistondianuuer and to compress said air in said cylinder during the power stroke of said piston-hammer, and means to conduct some of the air, so compressed, at high pressure, on every power stroke of said piston-hammer outwardly through said filter to clean the same of any accmnulation of dust thereon.

5. In an impact tool, the combination of a cylinder, a piston-hammer reciprocable therein on the principle of an internal combustion engine, an air filter, said piston-hammer cooperating with said cylinder to draw air through said filter into a portion of said cylinder during the return stroke of said piston-hammer and to compress said air in said cylinder during the power stroke of said piston-liammer, a valve operative to limit the pressure to which air may be compressed in said portion of said cylinder and means to convey the air passing said valve backwardly through said filter to clean the same on every power stroke of said piston-hammer.

6. In an impact tool, the combination of a cylinder, a piston-hammer reciprocable therein on the principle of an internal comtion engine, said piston-hammer dividing the interior of said cylinder into an explosion chamber, a fuel intake chamber, and an air compression chamber, said piston-hammer cooperating with said cylinder to draw air into said air compression chamber on the compression stroke of said piston-hammer and to compress said air in said air chamber on the power stroke of said piston-hammer and a valve adjustable to vary, limit and regulate the pressure to which air may be compre od in said air compression chamber of said cylinder to regulate the force of the blow delivered by said piston-hammer.

1'. In an impact tool, the combination of a cylinder, a piston-hammer reciprocable therein on the principle of an internal combustion engine, said piston-hammer cooperating with said cylinder to draw air into said cylinder on its compression stroke and to compress air in said cylinder on its forward or working stroke, means to receive the impact of said pision-hannner at the end of said working stroke and to transmit said impact to the shank of a tool, and means to limit and to vary the limit to which air may be compressed by said piston-hammer to regulatc the force of the impact: of said hanr ll lOl'.

S. In an impact tool, the combination of a c 'liuder, a pistondiammer reciprocable therein on the principle of an internal combustion engine, said cylinder being also provided with an air compression chamber, said piston-haminer cooperating with said cylinder to draw air into said air compression chamber on its compression stroke and to compress air in said chamber on its forward or working stroke, means to receive the impact of said piston-hammer at the end of the working stroke, and means to regulate and to vary the limit to which said. air may be compressed by said. pistondiammer to regulate and vary the force of the impact of said piston-hammer on said impact receiving means.

9. In an impact tool, the combination of a cylinder, a piston-hammer reciprocable therein on the principle of an internal comustion engine, means to supply fuel to said tool, means to receive the impact of said pistondnmuner at the end of the working stroke and to transi'nit said impact to a tool. and means independent of said fuel supplying means to regulate and vary the force of the said impact on said tool.

10. In an impact tool, the combination of a cylinder, a piston-hammer reciprocable therein on the principle o'l an internal combustion engine, said piston-hammer cooperating with the cylinder to draw air into a portion of said cylinder on its con'ipression stroke and to compress said air in said cylinder on its forward or working stroke, a conduit for conducting incoming air to said portion of said cylinder, a screen or filter in said conduit to remove dust from said incoming air, and means operative on said working stroke to convey air so compressed by said piston-hammer and at a predetermined high pressure from said cylinder to said filter, whereby the air passing outwardly through said screen or filter removes any accumulation of dust lrom the outer side of said screen or filter.

11. In an impact tool. the combination of a cylinder, a one-piece piston-hammer reciprocable therein on the principle ot a singleacting two-cycle combustion engine and having a cylindrical hole extending transversely therethrough and a rectangular recess at one end of said hole of a width not less than the diameter ot' said hole, and a cross-head 

